The effect of high protein diet on urea and guanidino compound levels in renal insufficient mice

Summary.: Nephrectomy in mice provokes a decrease in creatinine clearance (CTN_Cl) and an increase in urea and specific guanidino compound (GC) concentrations in blood and other tissues. Our purpose was to investigate the influence of high protein diet (HPD) on CTN_Cl, urea and GC levels in NX mice. Mice were nephrectomized or sham-operated and subdivided in groups to study five diet conditions. At the end of each experiment, 10 days and 30 days postsurgery, urine and blood were collected for determination of urea and GCs, including creatinine. HPD resulted in significantly higher CTN_Cl values in sham-operated mice than those observed in mice under normal protein diet, 10 days as well as 30 days postnephrectomy. HPD induced significant increases in plasma urea, guanidinosuccinic acid, argininic acid and α-keto-δ-guanidinovaleric acid concentration 10 days postsurgery but not 30 days postsurgery. HPD coincided with significantly higher excretion of urea, guanidinosuccinic acid, α-keto-δ-guanidinovaleric acid, creatine, argininic acid and γ-guanidinobutyric acid in sham-operated and nephrectomized mice 10 days postsurgery. Our results show that HPD induces supplementary (to nephrectomy) increases of urea and GCs in the early postsurgery period but not in the later phase.